Sen. Joe Lieberman is chafing Democrats with his opposition to President Barack Obama’s jobs bill and his flirtation with Republican presidential and Senate candidates. But with the Connecticut Independent retiring and Senate Democrats — with whom he caucuses — holding a slim 53-seat majority, there’s little they can do to rein him in.

They know it, and he seems to know it, too.

“Look, we have 53 Democrats in the Senate and need, at minimum, seven Republicans to join us to overcome incessant filibusters,” a senior Democratic Senate aide said. “Regardless of how Sen. Lieberman votes, the fact remains that we need Republican support to do anything and far too often we are left without it.”

Perhaps most disconcerting to Democrats have been Lieberman’s recent discussions with his state’s 2010 GOP Senate nominee, former World Wrestling Entertainment CEO Linda McMahon,&nbsp; and former Connecticut Rep. Christopher Shays (R), a longtime friend, to discuss their campaigns to capture his Senate seat in 2012.

With Democrats defending 23 seats next year — many of them vulnerable — the party’s majority appears seriously threatened. The party certainly needs to keep Lieberman’s blue state in the Democratic fold to retain its grip on power.

During a brief telephone interview, Lieberman said the two Republicans asked to talk to him. He said he would be happy to hold similar discussions with the Democratic candidates in the race if they request it; he said they have not. But the Senator said he wouldn’t apologize for the meetings, emphasizing that he was elected as an Independent in 2006 and that he would continue to conduct himself as such.

“My ultimate loyalty is to do what’s right for the country. I don’t mean that to be self-righteous; I just think that’s what my job is,” Lieberman said.

The Senator said he is neutral in both the Connecticut Senate race and the presidential race, but he did not exclude the possibility of endorsing a Republican in one or both races. He said he has not decided whether he’ll endorse in either race nor which party’s candidates he’ll support.

Lieberman defended his voting record, noting that he recently joined with all&nbsp; the other members of the Democratic Conference to end a GOP filibuster of Obama’s jobs bill and that he pushed aggressively to end the “don’t ask, don’t tell” policy that barred gays from serving openly in the military since 1993.

&nbsp;The Senator said neither Senate Majority Leader Harry Reid (Nev.) nor other Democrats have complained to him about his recent votes or communications with GOP Senate candidates. Lieberman said he and Reid remain on very good terms.&nbsp;

But he otherwise made it clear that he has no intention of backing off, even if that irks his Democratic colleagues.

“It’s who I am and also what I believe is my responsibility, which is to do what I think is right,” Lieberman said. “I know in an age of intense partisanship I’m unusual, but that’s just the way it is.”

Lieberman was re-elected in 2006 on his own “Independent Democrat” ticket after losing the Democratic primary. In that race, some of his Senate colleagues supported the winner, Ned Lamont, who campaigned against Lieberman because of his support for the Iraq War. The experience appeared to make Lieberman feel that he needn’t be as loyal to the party as he had been in the past, and consequently, it made him less likely to win re-election in 2012. After four terms in the Senate and a historic stint as the party’s 2000 nominee for vice president, he announced in January that he would retire.

Of all the sins against his party, the greatest was probably his decision to endorse Sen. John McCain (R-Ariz.) for president in 2008 and to campaign aggressively on his behalf. That led some Democrats to call for his ouster as Senate Homeland Security and Governmental Affairs chairman.

But at the urging of Obama and Reid, Lieberman and Senate Democrats reconciled, negotiating a mutually agreed-upon deal that stripped the Connecticut Member of his seat on the Environment and Public Works Committee. They allowed him to maintain his chairmanship of the Homeland Security panel as well as his leadership of an Armed Services subcommittee.

Lieberman said at the time that the Conference would not “regret” the decision, while Senate Democrats made it clear that they expected Lieberman to be loyal and support their agenda.

The honeymoon was short. Lieberman threatened to filibuster elements of Obama’s health care reform proposal championed by the Senate’s more liberal Democrats — opposition that was considered a serious impediment to the bill’s passage at the time. However, changes were made that gained his vote for the final version of the bill. Recently, his aggressive opposition to top Democratic initiatives has resurfaced.

He has been notably critical of most aspects of the president’s $447 billion jobs plan and referred to Friday’s announcement from Obama that all American troops will leave Iraq by year’s end as “a statement of failure, not success” that could endanger what the U.S. has achieved during the war. Additionally, he has declined to commit to support Obama’s re-election or the party’s eventual nominee for his Senate seat.

Democrats are none too pleased.

“At this point, it’s safe to say many in the Democratic caucus see Sen. Lieberman as a mosquito,” said Jimmy Williams, a former aide to Senate Majority Whip Dick Durbin (D-Ill.). “The bad news is he has sucked enough blood from both sides of the aisle. The good news is winter is coming, meaning his time in the Senate will thankfully come to an end.”

Lieberman’s pending departure from Capitol Hill would appear to render useless any punitive measures on the part of Senate Democrats to quell his recent actions. However, the fact that Lieberman is retiring has also diminished the sting of the disappointment many Democrats feel because of the Senator’s behavior. One Democratic strategist described the feeling in the Conference as one of “indifference,” adding: “It’s just Joe being Joe.”

But another Democratic operative said there is palpable discontent within the Conference, particularly over Lieberman’s willingness to meet with and potentially advise Republican Senate candidates vying to replace him.

Still, Democrats concede they can ill afford to chase a Member out of the Conference given the fact that their majority rests on four seats.

“Advising Republican candidates for his own Senate seat is pretty outrageous and runs against what he said he’d do. I think folks are increasingly concerned again,” a Democratic Senate aide said. “But he’s got a year left and we only have 53 votes, so there is frustration, but better to have him inside the tent ... than outside.”